At least if we're playing South Africa, we can't get Kaplan.
So the 10 referees are:
Barnes, Wayne (RFU) - 2007 QF
Poite, Romain (FFR)
Owens, Nigel (WRU)
Rolland, Alain (IRFU) - 2003 QF, 2007 QF and Final
Walsh, Steve (ARU) - 2003 QF, 2007 SF
Lawrence, Bryce (NZRU)
Clancy, George (IRFU)
Kaplan, Jonathan (SARU) - 2003 QF, 2007 SF
Joubert, Craig (SARU)
Pearson, Dave (RFU)
Going from the last two RWC, you'd have to think that Steve Walsh, Jonathan Kaplan and Alain Rolland are the most likely chances of getting the final.
If you made the assumption that Alain Rolland wasn't going to get another final then I'd say Kaplan is a legitimate chance at getting the final unless South Africa make it. If New Zealand make it, I wonder if that rules out Steve Walsh as well or whether he'd just be barred from Australian games?
I'd guess that Wayne Barnes gets the semi final on the Aus/SA/NZ side of the draw and Steve Walsh gets the semi on the Eng/Ire/Wal/Fra side of the draw.
Kaplan would get one of the QFs and the other three might be Joubert, Rolland, and Lawrence.